The Martinet dioxindole synthesis is a chemical reaction used to synthesize dioxindoles 3 from anilines and esters of mesoxalic acid 1.[1][2]
Heating a N-substituted aniline in the presence of an ester of mesoxalic acid 1 will produce the dioxindole 2. Heating of 2 in the presence of water will hydrolyze the remaining ester, and effect a decarboxylation to give the desired dioxindole 3.